Warp knit fabric containing loose filling and having unfrayed selvage



' May 20, 1969 N .SHARPE 3,444,707

WARP KNIT FABRIC TAINI LOOSE FILLING AND HAVING UNFRAYB ELVAGE Filed Sept. 7. 1967 Sheet of 5 1,293 INVENTOR l [V50 1? Si/41W: a I

5 kzw d lzqM ATTORNEYJ May 20, 1969 N. K. SHARPE 3,444,707

WARP KNIT FABRIC CONTAINING LOOSE FILLING AND HAVING UNFRAYED SELVAGE Filed Sept. 7, 1967 Sheet 2 of s r ,%eaeoeoooeoo.

\ wsi 'tr INVENTOR May 20, 1969 N. K. SHARPE 3 ,7

WARP KNIT FABRIC cou'mnuue LOOSE FILLING AND HAVING UNFRAYED SELVAGE 3 Filed Sept 7 1967 of 5 Sheet INVENTOR May 20, 1969 N. K. SHARPE 3,444,707

WARP KNIT FABRIC CONTAINING LOOSE FILLING AND HAVING UNFRAYED SELVAGE 4 Sheet of 5 Filed Sept. '2, 1967 3 "ll INVENTOR A427 1 Jay/era L %@@Z,/ M

ATTORNEYS May 20, 1969 v N. k. SHA RF'E 3,444,707

WARP KNIT FABRIC CONTAINING LOOSE FILLING AND HAVING UNFRAYED SELVAGE 5 Sheet of 5 Filld Sept. 7. 1967 INVENTOR 1V2? KJHHPPE Z4MpZ4 m@ Y V ATTQRNEY$ United States Patent "ice 3 444 707 WARP KNIT FABRIC CONTAINING LOOSE FILL- ING AND HAVING UNFRAYED SELVAGE Ned K. Sharpe, Greensboro, N.C., assignor to Burlington Industries, Inc., Greensboro, N.(., a corporation of Delaware Filed Sept. 7, 1967, Ser. No. 666,057 Int. Cl. D04b 23/10 US. Cl. 66-190 3 Claims ABSTRACT OF THE DISCLOSURE A warp knit fabric knitted through a base material forming chain stitches of two yarns, alternately forming stitches in adjacent wales. The end most chain having one yarn.

forming stitches alternately with the adjacent wale and another yarn forming stitches alternately in the same chain.

The present invention relates to a fabric and apparatus and method for making a fabric. More specifically, it pertains to a kind of fabric having loose fibers or filling yarn laid in and bound together with interlocking chain stitches produced by warp knitting. Each chain of stitches is made from yarn which alternately forms stitches in adjacent rows.

For purposes of simplicity, the term sewing will be used herein to refer to the warp knitting operation. This term has found use in the textile industry in connection with this kind of fabric and avoids confusion because the word warp is used to refer to another yarn sometimes used in this type of fabric, as will be explained below. Similarly, for convenience, the threads which form these loops are referred to as sewing thread.

Fabrics of this type can be made by forming a plurality of chain stitched rows of loops of sewing thread along an array of loose fibers or loose filling yarn. The stitches pass through the material at spaced points along the machine direction of the fabric and gather the filling yarn, and to a certain extent the loose fibers, into a plurality of clusters separated by spaces corresponding to the stitch insertion points. A plurality of stitches are formed simultaneously across the material, so that the spaces tend to be essentially continuous across the fabric, especially where yarns are used as the filling.

The present invention is concerned with one kind of this class of fabrics, in which the stitches of adjacent chains are interlocked, that is a tricot stitch. This effect is obtained by the manner in which the sewing thread is supplied to loop forming needles. The thread passes through guides which oscillate between adjacent needles. Each sewing thread end is alternately supplied to adjacent sewing needles, and each chain contains loops alternately formed from two different threads.

This type of stitch has several advantages. First, the intar-knitting of the two sewing ends increases the durability of the fabric. If simple chain stitching is used, one break in a sewing thread may result in an entire chain of loops being pulled out. In the interlocking stitch described above, each sewing thread is interlocked with two others; therefore, a broken thread will be held by two others.

Another advantage of this type of stitch is that it facilitates the use of warp yarns. It is known that dimensional stability of the fabric can be improved by laying warp yarns against one side of the filling material and fastening them down with sewing thread. In the interlocking stitch, zigzagging of sewing thread between adjacent chains of loops provides a convenient means for holding the warp yarn in place. The warp yarn is simply laid against the fabric before the sewing thread is moved over it by the sewing thread guide.

3,444,707 Patented May 20, 1969 However, the interlocking chain stitch has an important disadvantage. That is, it results in loose threads at the sides of the fabric and a rough or irregular edge. This can best be understood by first considering the simple chain stitch. With that type of stitch, the loose filling yarns are held in clusters by the sewing thread as explained above. On one side of the filling, there is a loop for each stitch, and, on the other side of the filling, there is the sewing thread connecting between adjacent loops. Whereas the connecting thread zigzags between adjacent chains in the interlocking chain stitch, in the simple chain stitch it follows the same line as the loops. Therefore, at the edge of the simple chain-stitched fabric, the clusters of loose filling yarns are held together between the loops on one side and the connecting threads on the other side. by cutting the filling close to the last chain of loops, a neat unfrayed edge can be produced.

This cannot be accomplished in the warp knitting machines which employ the interlocking stitch. In this type of machine, at the edge of the fabric, two sewing threads form loops in the last chain. The first of these also is formed into loops in the next to the last chain. The second is used in alternate loops in the last chain. However, when the first thread is transferred to the needle which produces the last chain of loops, the second thread is transferred to the needle which is beyond the last chain. The second thread is formed into a loop by the needle, and then transferred back to the needle which forms the last chain, in time for the next stitch. Since this next needle is not supplied with sewing thread to form a next stitch, the loop that it has just formed remains loose. Ultimately, it will pull out, leaving loose thread in the last chain of stitches.

This construction has several disadvantages. First, the loose thread in the last chain can result in loosening the entire chain, and is easily snagged. Second, the loose filling fibers or yarn are not properly held in clusters and give the edge a frayed appearance. Any attempt to trim the fabric close to the last chain of stitches will still leave the filling loose in each cluster.

It might seem possible to simply remove the next needle so that loose loops will not be formed. However, this is not convenient. For example, needles usually are supplied in sets of, say, ten, mounted on a single lead. It would be very difiicult to provide independent mounting of the needles unless they are spaced too far apart. Since a machine is used to produce a variety of widths of fabrics, it is supplied with needle sets across its full width, and the width of the fabric produced is determined by the number of sewing threads supplied. Therefore, removing the next needle would require limiting the variety of fabric widths to that corresponding to a number of needle sets, or modifying needle sets by removing individual needles. Neither is satisfactory.

A principal object of the present invention is to provide a fabric which avoids the above-described difiiculty. Other objects are to provide a method of producing such a fabric and apparatus for carrying out the method.

In accordance with the present invention, the loose loops described above are pulled out before the sewing thread which forms them completes formation of another loop. Therefore, this sewing thread forms alternate loops in the last chain; the portion of that thread connecting between loops follows the chain of loops similar to the thread in simple chain stitching. This thread, then, tightly binds the clusters of loose filling along a straight line. If the fabric is sheared close to this line, it will have a neat, unfrayed edge.

Briefly stated, in accordance with a preferred embodiment, the above-described loose loop is pulled out by a resilient thread guide whose resilience is overcome by yarn tension when the loose loop is formed, but which recovers as soon as the loop is cast off a needle, thereby pulling the loop open.

As used herein, the term resilient is intended to describe a member possessing resilience. The term resilience, for present purposes, refers to the ability of a body to recover its size and shape after being deformed, by stretching, compression or the like. Therefore, the term resilient thread guide refers to a member in contact with the thread which is displaced when a loop is formed in that thread but which resumes its original position when the loop is cast ofi.

Various types of material can be formed into a fabric by sewing in accordance with the present invention. One preferred form of material is described in US. Patent 2,890,579. A plurality of loose filling yarns are provided from continuous yarns which are wound back .and forth across a kind of tenter frame by a carriage, and around heddle hooks on moving conveyor belts at either side of the frame. The conveyors are moving while the carriage traverses the space between them, so that the filling threads are more or less oblique to the machine direction and in two sets which are oblique to each other. That is after a set of parallel threads are caught on the hooks of one of the conveyors, the carriage moves directly across to the other conveyor. While the carriage moves across, the conveyors are moving perpendicularly to the carriage and, by the time the carriage reaches the other conveyor, that other conveyor has moved a short distance. Therefore the heddle hooks on which the threads are caught on the second conveyor are not directly opposite the hooks used on the first conveyor, and the threads are oblique to the machine direction. When the carriage returns to the first conveyor, an opposite effect is observed, and the threads laid down are oblique to the machine direction and to the threads laid down in the previous traverse.

Subsantially any textile fibers can be used for the warp, filling and/or sewing thread. These include natural fibers such as cotton, wool, sisal, linen, jute and silk, man-made fibers and filaments such as regenerated cellulose rayon, polynosic rayon, cellulose esters, e.g. cellulose acetate, cellulose acetate/butyrate and cellulose triacetate and synthetic fibers and filaments such as acrylics, e.g. polyacrylonitrile, modacrylics such as acrylonitn'le-vinyl chloride copolymers, polyamides e.g. polyhexamethylene adipamide (nylon 66), polycaproamide (nylon 6) and polyundecanoamide (nylon 11), polyolefin, e.g. polyethylene and polypropylene, polyester, e.g. polyethylene terephthalate, rubber and synthetic rubber, saran, glass, and the like. Sewing yarn sizes ordinarily are 15 to 1100 denier and filling yarns 15 to 3300 denier. When warp yarns are used, they may be, e.g. 15 to 6600 denier. Normally, stitches will be 0.4 to 4 mm. apart along the warp and about 1.13 to 3.57 mm. apart across the fabric. Typically, the sewn fabric weighs 2 to 35 ounces per square yard.

The filling threads mentioned above are cast off the heddle hooks after they are caught up by loops of sewing threads which gather them into clusters, separated by spaces where the sewing thread passes through the fabric. At the edges of the fabric, the filling threads reverse direction and form loops extending beyond the last chain of stitches. Alternately, these edge loops are severed from the body of the fabric, in the hope of producing a neat edge. Prior to the present invention, when interlocking chain stitching was used, a neat edge was not possible because of the loose sewing thread in the last stitch chain, as described above.

Another type of loose filling material which can be used in this type of fabric is a batting or non-woven fiber web. This is a web of loosely arrayed fibers of any of the types previously mentioned, extending more or less randomly in various directions. Webs of this type may be formed by depositing atmospherically suspended fibers onto a movingscreen, for example by suction applied through the screen. Webs also can be produced by carding a picker lap, and thickness can be increased by cross-laying a web in known manner. Strictly speaking, a batting or the like cannot be described as loose filling because the fibers are arranged more or less randomly in all directions. However, since a portion of the fibers will be more or less transverse or oblique to the loop chains, especially when derived from a cross-layed carded web, it can be considered to comprise loose filling for purposes of the present invention. Depending upon the relationship between the fibers, fabrics of this type may exhibit a tendency for the filling to be gathered into clusters by the sewing thread.

The invention will be better understood from the following detailed description of preferred embodiments, reference being made to the drawing, in which:

- FIGURE 1 is a perspective view of the portion of the apparatus where loop chains are formed;

FIGURE 2 is a plan view of the apparatus, some parts being omitted for clarity;

FIGURE 3 is a cross-section of a portion of the apparatus;

FIGURE 4 is a cross-section similar to FIG. 3 but showing the parts after they have moved in the next step of operation;

FIGURE 5 is a schematic drawing showing the path of movement of a thread guide about adjacent sewing needles;

FIGURE 6 is a view of the fabric on greatly enlarged scale, the filling material being omitted for clarity;

FIGURE 7 is a perspective view, on greatly enlarged scale, of a portion of the apparatus but with some parts omitted for clarity showing sewing thread being layed into the sewing needles;

FIGURE 8 is a view similar to FIG. 7, but at a subsequent stage in the operation;

FIGURE 9 is a plan view, partially in section, of a portion of the apparatus showing the means for operating the needles and thread guides; and

FIGURE 10 is a cross-section along lines 10'10 of FIG. 9.

As seen in FIG. 6, the sewing thread in the fabric is formed into interlocked chain stitching substantially along the warp or machine direction. Each sewing thread 1 is formed into a plurality of loops 2 spaced along the length of the fabric, each loop passing through the fabric. The loops are formed into parallel chains, but each chain is formed from two threads which alternately are formed into stitches of adjacent chains. For example, one chain of loops, designated 3 in the drawing, is formed from two threads 4 and 5. A first loop 6 is formed from thread4, the next loop 7 is formed from thread 5 and the nextloop 8 is formed again from thread 4, etc. Thread 4 also is formed into loops 9 in the chain 10 on one side of chain 3, alongside loop 7 and other loops in chain 3 which are formed from thread 5. Similarly, thread 5 also is formed into loops 11 in a chain 12 on the other side of chain 3, alongside loops 6 and 8 in chain 3. The arrangement is such that each sewing thread is interlocked with two others in adjacent stitch lines so that, if a thread breaks, it will not pull out a succession of stitches as it would if each chain were formed from a single thread.

The formation of this chain stitching is illustrated in FIGS. 3 and 4. A needle 20 is provided which has a point 21 at one end and a hook 22 adjacent the end. There is a groove 23 in the upper surface of the needle in which slides part of a bent wire latch 24. The needle is mounted for horizontal reciprocating motion.

A web 25 moves downwardly across the path of the needle, and as the needle reciprocates-it alternately pierces and is withdrawn from the web, the web being advanced downwardly while the needle is withdrawn.

A thread guide 26 is provided to insert the sewing thread 27 into the book 22 when the needle extends through the web. As can be seen by comparing FIGS. 3 and 4, the thread guide moves up alongside the needle, across it and down on the opposite side, laying the thread in the hook 22 as it moves across. Then the needle is retracted and the latch 24 moves across the hook. At the same time, the web 25 moves down past the needle. As the needle moves forward to receive sewing thread again, the thread previously placed in the hook slides back onto the shank of the needle as seen at 28 to form a loop 29. When the needle retracts again and the latch 24 closes, the loop 29 slides forward toward the tip of the needle, pushed if necessary by the upright portion of latch 24. Since the hook 22 is closed by the latch, the loop 29 shdes over the hook and is cast off the point 21 of the needle. At the same time, the thread in the hook is pulled through loop 29.

The thread guide 26 is mounted to alternately move up and across two needles, designated 201 and 202 m FIG. 5. Therefore, it describes a figure eight path 30.

The problem which the present invention avoids can best be understood from FIG. 5. Assuming that a needle 201 is the needle at the edge of the fabric being manufacturcd, one thread guide designated 261 (see l-TIG. 1) describes the path 30 and alternately lays thread 1nto needles 201 and 202. An adjacent thread guide 262 alternately lays thread in needle 202 and the needle 203 whlch is adjacent to needle 202. Thus, when the thread gulde 261 is laying thread into needle 201, thread gulde 262 1s laying thread into needle 202. When the next stitch 1s formed, thread guides 261 and 262 lay thread into needles 202 and 203, respectively. But no thread is laid 1nto needle 201. Therefore, when needle 201 is retracted, the loop on its shank is cast off, but there is no thread in its hook to pull through the loop. Therefore, that loop is left loose.

The present invention provides means for pulling out that loop before another loop is formed by needle 201, so that the thread is pulled tight behind the line of loops formed by needle 202. As seen in FIGS. 1, 7 and 8, this is accomplished by a resilient thread guide 31 over which passes the thread supplied to the thread guide 261. The resilient thread guide 31 is a piece of spring steel, firmly mounted at one end to the frame of the apparatus, for example by a block 32. The free end of the resilient thread guide 31 is bent to form a kind of hook 33 over which the sewing thread passes. There also is a single loop 34 formed in the 'wire between its ends, to give it controlled resilience. The resilience of the guide 31 is sufficiently weak to be overcome by thread tension when a loop is formed by needle 201, but sufficiently strong to pull out a loose loop of thread after it is cast off the needle 201. Thus, when a loop is formed on needle 201, the thread pulls the guide 31 down, and when the loop is cast off and is loose, the guide 31 elevates and pulls out the loose loop. This sequence is illustrated diagrammatically in FIGURES 7 and 8.

For rapid machine operation, it is advisable to use circular eccentric cams for actuating the needles and the thread guides. As shown in FIG. 9, a needle bar 40 carrying the needles 20' is actuated by a connecting rod 41 extending from an eccentric rod 42 linked by a strap 43 of an eccentric cam 44 which is rotated by the motor-driven shaft 45 supported by a housing 46. Similarly, the reciprocating movement of the latches 24 required for closing the hooks of the needles is obtained by means of an eccentric cam 47 cooperating with a strap 48 actuating, through an eccentric rod 49, a connecting rod 50 that actuates the brackets to which the latches 24 are attached through a cam. The holders of the thread guides 26 are fastened to a guide bar 51 which, by means of suitably attached lever arms 52, is fixedly mounted on a shaft 53. This shaft, being rotatably mounted within bearings 54, is adapted to slide longitudinally back and forth and carries a short lever 55.

Lever 55 is connected with a coupling rod 56 linked to an eccentric rod 57. Rod 57 with its strap 58 encloses the eccentric cam 59 which, by means of an intermediate connecting rod 60, moves the thread guides up and down. Aside from this reciprocating movement, the thread guides must undergo an axially transverse back and forth movement in order to insert threads into the hooks of the needles and to alternate between needles. For this pur pose, the thread guides 26 and the shaft 53 carrying the same are operated to perform one complete back and forth movement while the needles are moved twice in and out. To accomplish this, a pinion 61 keyed to the shaft 45 engages a spur wheel 62 of twice its size. Consequently, the spur wheel rotates at half of the speed of the shaft 45.

Spur wheel 62 is fixedly connected with an eccentric cam 63 whose strap member 64 is linked by an eccentric rod 65 to a connecting rod 66 axially slidable in a bearing 67. When in operation, the rod 66 and its linkage 68 impart axial reciprocation to the shaft 53 by actuating an angle lever 69 rotatably mounted to a pivot 70. The tension spring 71 fastened about the shaft 53, between one of the bearings '54 and the adjacent lever arm 52 of the guide bar 51 aids the axially oscillating movement by forcing the shaft against an adjusting screw 72 connecting the free end of angle lever 69 to that of the shaft 53.

The filling yarn supply is illustrated in FIG. 2. For simplicity, a single yarn is shown, indicated by the numeral 80. At opposite sides of the apparatus, there are chains 81 and 82, each trained around sprocket wheels and driven by a motor, not shown. On each of the chains 81 and 82 there are a plurality of upright heddle hooks 83 around which the yarn is wound. Filling yarn is laid in place by a yarn guide mounted on a mobile carriage 84 which is traversed back and forth above the chains 81 and 82. The arrangement is such that as the carriage moves a bit past the hooks on one side of the chains, the chain moves and the yarn is turned around one or more hooks. Then the carriage moves in the opposite direction across to the other chain and past that chain so that the procedure is repeated.

In actual practice, the carriage 84 carries several yarn guides and a plurality of yarn ends is laid down as superimposed layers, each layer being at an angle to the layer next to it. The filling yarn remains in this position until loops are formed by the sewing operation, and the filling is cast off the chains 81 and 82. Then the filling takes the forms of generally parallel clusters of yarn separated by spaces at sewing thread stitch insertion points.

In lieu of this type of filling yarns, various types of non-woven materials may be used. They may be supplied from a beam and carried to the sewing needles by the chains 81 and 82.

In some cases, the fabric may use warp yarn which is simply laid under the sewing thread and against the filling. The warp yarn is supplied downwardly against the filling through a yarn guide 91 as seen in FIG. 1.

A special arrangement must be provided for supplying the sewing thread. In the conventional machine described previously, a single sewing yarn package supplies a plurality of ends, one for each thread guide. However, in using the present invention, this is not possible because the outermost sewing thread forms only one half as many loops as threads forming loops at the interior of the fabric. To maintain proper tension, it is necessary that the outermost sewing thread not unwind from the package at the same rate as other threads. Therefore, in accordance with the present invention, the outermost sewing thread is supplied from a separate package, capable of unwinding at a different speed from thread used at the interior of the package. The arrangement is illustrated in FIG. 2 in which three sewing yarn packages are indicated by the numerals 95, 96 and 97 on a beam 98. Sewing thread ends are supplied from these packages through appropriate thread guides and tensioning devices, not shown, to the thread guides 26 which lay them into the sewing needles 20. The packages 96 and 97 each supply one end to the outermost thread guides 20 while the package 95 supplies a plurality of ends to the other thread guides 20. All three packages are mounted on the beam 98 to be capable of rotation at separate speeds. If the package 95 is mounted to the beam and the beam is rotatable, the packages 96 and 97 must be mounted on the beam with bearings to rotate independently. If the packages are unwound by a power drive, rather than through thread tension, obviously packages 96 and 97 must be driven at slower speed than the package 95, i.e. at about half speed.

Various changes may be made in details of construction and mode of operation without departing from the scope of the invention, as defined in the appended claims.

What is claimed is:

1. In a fabric having a filling comprising a plurality of loose filling yarns or fibers and a plurality of chains of loops of sewing threads along one side of said filling generally perpendicular to said loose filling yarns or fibers with sewing thread connected between loops extending through said filling and along the other side of said filling,

the sewing threads in said fabric alternately forming loops in adjacent chains and each chain containing loops alternately formed of two different sewing threads;

the improvement in which a laterally outermost chain of loops is formed of (a) a first sewing thread which alternately forms loops in said outermost chain and in the chain next to it and (b) a second sewing thread which only forms loops in said outermost chain alternately with loops formed from said first sewing thread and the portions of said second sewing thread connecting between loops being substantially taut against said other side of said filling and substantially in line with said outermost chain of loops.

2. A fabric as set forth in claim 1 in which said filling comprises loose filling yarns gathered into substantially parallel clusters separated by spaces where said sewing thread passes through said filling.

3. A fabric as set forth in claim 1 in which said filling comprises a carded non-woven fiber web.

References Cited UNITED STATES PATENTS 2,442,796 6/1948 Young 6686 3,262,287 7/1966 Woodcock 6690 3,274,805 9/1966 Duhl 6684 3,365,918 1/1968 Hughes 6685 RONALD FELDBAUM, Primary Examiner.

US. Cl. X.R. 66193 

